The present invention relates to the field of submersible cargo vessels, and in particular it relates to a self-leveling ballast control system for vessels such as submersible barges and dry docks.
The use of submersible barges to transport cargo such as marine dredging equipment is becoming increasingly popular. Typically, the loading and unloading of such barges is accomplished by controllably submerging one end of the barge and floating cargo on or off. This controlled submergence, which is accomplished by controllably flooding one or more ballast compartments in the barge hull, is a delicate process, since both longitudinal and lateral stability must be maintained. Furthermore, the danger of having the barge go vertical due to errors in flooding control, is ever present.
Likewise, the raising of the barge, especially when the cargo has been loaded thereon, is an operation which requires a great deal of care to avoid instabilities which can capsize the vessel. Thus, the proper positioning and securing of the cargo is crucial, as is the requirement for maintaining the barge in a proper attitude in all directions while it is being raised.
Therefore, in view of the extreme care required during the loading and unloading of such barges, the complete cycle of submerging the barge, loading or unloading the cargo, and raising the barge typically requires at least six hours, and it is not unusual for the whole process to take an entire day or more.
Accordingly, the need has been felt for a submersible barge which can be quickly and safely submerged and raised with a high degree of stability. In my co-pending application, Ser. No. 933,591, filed Aug. 14, 1978, I disclose a submersible, floating vessel which can be submerged and raised quickly, and which is self-leveling during the raising process. However, it would be advantageous to provide a system with which existing barges and the like can be retrofitted to achieve the same results.